A conventional electric train running in an alternating-current electrified section is provided with a power conversion apparatus (hereinafter, referred to as a “main conversion apparatus”) including a converter unit to convert an alternating-current to a direct-current, an inverter unit to convert a direct-current to an alternating-current, and other components. The main conversion apparatus is provided with a fan to cool down semiconductor devices employed in the converter unit and the inverter unit.
Recently, due to increased demands for reduction in size and weight also in the technical field of electric trains, downsizing and weight saving of the main conversion apparatus have been sought. Patent Document 1 discloses a technique in which by using wind (hereinafter, referred to as “traveling wind”) that flows outside a vehicle during running of an electric train in order to cool down a semiconductor device in the main conversion apparatus, the fan in the main conversion apparatus is abolished to thereby promote downsizing and weight saving of the main conversion apparatus. Specifically, a technique is disclosed in which a main conversion apparatus is mounted under a vehicle floor, and the main conversion apparatus is cooled down by means of traveling wind between tracks and a bottom surface of the vehicle.